Question: $ D = \left[\begin{array}{rrr}0 & 0 & 1 \\ 0 & 2 & 1 \\ 1 & 1 & 0\end{array}\right]$ What is $ D^{-1}$ ?
Explanation: $ = \left[\begin{array}{rrr}\frac{1}{2} & -\frac{1}{2} & 1 \\ -\frac{1}{2} & \frac{1}{2} & 0 \\ 1 & 0 & 0\end{array}\right]$